The trick you missed in Serena’s new video

TENNIS star Serena Williams is the picture of maternal pride as she lovingly cradles her baby daughter Alexis Olympia Ohanian in her new Gatorade ad.

There's just one catch - it turns out the adorable little girl in the commercial is not her child.

The sports drink giant recently released the big-budget ad, which appears to show Williams cuddling her three-month-old daughter as she shares lessons she's learned from her remarkable career.

Tennis star Serena Williams cradles a baby — not her own — in her new Gatorade ad.

In the voiceover, Williams is heard telling her child that even though it's okay if she "never picks up a racquet", she hopes that when it comes to "the game of life" her daughter "keeps playing, no matter what".

E Online reports that Gatorade hired a body double to play three-month-old Olympia after the child became sick.

The child used in the ad has been revealed as a body double for baby Olympia.

Fans will no doubt be disappointed that the baby in the ad is not the real Olympia. Gatorade, however, told advertising journal AdAge that the message of the commercial - which aims to inspire young girls and women - is the same.

"While Serena intended to have Olympia make her screen debut as part of this film, her daughter was under the weather and unable to be on set, but the sentiment remains the same," a Gatorade spokeswoman told AdAge in an email.

Olympia Ohanian may be just three months old, but she has already had her fair share of the spotlight.

Unlike some celebrities who prefer to keep their children's profiles low-key, Williams has set up an Instagram account in her baby daughter's name, with the bio stating "Everything here is from Mama and Daddy".

The little girl also featured in the photographs of her parents' lavish star-studded wedding in New Orleans on November 16.